1. Field of the Invention
The present invention relates to a light source module, a light source apparatus and a liquid crystal display, using light emitting diodes (LEDs) as light sources.
2. Description of the Related Art
Liquid crystal displays (LCDs) are lower in power consumption than cathode ray tubes (CRTs), and can be reduced in size and in thickness. At present, liquid crystal displays in various sizes are widely used for apparatuses ranging from small ones such as portable phones, digital cameras, PDA (Personal Digital Assistants), etc. to large-sized liquid crystal TV sets.
The liquid crystal displays are classified into the transmission type, the reflection type and the like. Particularly, a transmission type liquid crystal display includes a backlight unit as an illuminating light source, in addition to a liquid crystal display panel having a liquid crystal layer sandwiched between a pair of transparent substrates. The backlight unit may be of the underneath type in which the light source is disposed underneath the liquid crystal display panel, or of the edge light type. For large-screen liquid crystal TV sets known as thin-type TV sets, the underneath-type backlight units are widely used.
As a light source for the backlight unit, CCFLs (Cold Cathode Fluorescent Lamps) have been being widely used. In recent years, LED backlight units having light emitting diodes (LEDs) for three primary colors, i.e., R (red), G (green) and B (blue) colors, as light sources are widely used so as to enhance the reproducibility of the display colors. The underneath-type LED backlight units include those in which LEDs for the RGB colors are arranged two-dimensionally in a plane to obtain white light (refer to Japanese Patent Laid-open No. 2005-352427 as referred to as Patent Document 1 hereinafter).
For example, Patent Document 1 discloses a light source module 42 in which, as shown in FIG. 13, a plurality of LED devices 40R, 40G, 40B for RGB colors are arranged in a predetermined order on the same axis line on a wiring board 41, and discloses a light source apparatus in which a plurality of such light source modules 42 are combined two-dimensionally to constitute an in-plane light source. The light source apparatus is used as a backlight apparatus for illuminating a liquid crystal display panel, from the back side, with white light obtained by operating the color LEDs to emit color rays and mixing the color rays.